Historically, studies of language disorder and grammatical error patterns have been primarily done on English-speaking children. For Spanish-speaking children, most recent studies have been mostly on bilingual Spanish–English speakers, who may have different error patterns than monolingual Spanish speakers. This study describes the error patterns of 49 monolingual Spanish-speaking children with language disorders (traditional ‘SLI’—so these children all had IQs > 85 and no other developmental disorders). The researchers found that:

articles were most frequently in error; in Spanish, this is “el” or “la” ( = the), “un” (= a)

prepositions were also found to be difficult for these children; in Spanish, this is “por” (= through, for), “de” (= of)

Most important is recognition that this pattern is different than what is observed in English-speaking children with language disorders. The authors state: “In particular, auxiliaries are less sensitive to SLI in Spanish than in English. In contrast, articles, clitics, prepositions, and connector words are more vulnerable in Spanish than in English.” Thus, error patterns of language disorder are unique to the language the child speaks. When trying to differentiate Spanish-speaking students with language disorder from those without, the authors found the strongest predictors were utterance-level grammaticality and excessive word or morphological omissions.